1. Field of the Invention
This invention relates to an anti-corrosive additive composition for concrete compositions, and more particularly to an anti-corrosive additive composition for concrete compositions used in reinforced concrete structures.
2. Description of the Prior Art
For structures made of reinforced concrete, concrete has at least two functions, i.e. to absorb compressive strains and to protect reinforcing steel bars or re-bars against corrosion. The re-bars function to absorb shear and tensile stress.
The cost of corrosion is annually estimated to be in the billions with concomitant catastrophic collapses of structures and losses in lives. The protective effect of hardened concrete on re-bars depends, inter alia, on climatic and environmental conditions as a function of amount of cement, grain of concrete aggregate, water/cement factor and concrete compression.
In U.S. Pat. No. 4,869,752 to Jaklin, there is described the use of modified inorganic silicates, e.g. modified alkali silicates as a concrete additive to prevent corrosion of steel structures or steel re-bars.
In U.S. Pat. No. 6,277,450 to Katoot, there is described the use of a coating process to coat the surface of the metals which is modified to an active moiety of metal hydroxide receptive to a fully cross-lined polymer of various thickness.
In copending application U.S. Ser. No. 10/447,975, there is disclosed an anticorrosive additive comprised of an alkali based solution of dioic acid, alone or in admixture with other compositions for an anti-corrosion additive for concrete compositions providing for more effective corrosion protection for longer periods of time obviating costly precoating of surfaces of metals used in the building and construction industry.
However, there is a need for inclusion of a composition in the anticorrosive additive to reduce excessive air entrainment or foaming during preparation of concrete mixes and for controlled air content of the cured concrete. To improve freeze/thaw properties, it is most effective to control air entrainment within cured concrete to about 5 to 8% with evenly spaced apart bubbles having a specific surface of from 600 to 1,100 square inches per cubic inch spaced apart by 0.004 to 0.008 inches.